Broadband light funneling in ultrasubwavelength channels having periodic connected unfilled apertures
A structure for broadband light funneling comprises a two-dimensional periodic array of connected ultrasubwavelength apertures, each aperture comprising a large sub-aperture that aids in the coupling of the incoming incident light and a small sub-aperture that funnels a significant fraction of the incident light power. The structure possesses all the capabilities of prior extraordinary optical transmission platforms, yet operates nonresonantly on a distinctly different mechanism. The structure demonstrates efficient ultrabroadband funneling of optical power confined in an area as small as ˜(λ/500) 2 , where optical fields are enhanced, thus exhibiting functional possibilities beyond resonant platforms.
1. A structure for broadband light tunneling, comprising a two-dimensional periodic array of unit cells in a thin conducting film, wherein the unit cells have a first periodicity in a first dimension and a second periodicity in a second dimension, wherein the unit cells are ultrasubwavelength to an incident light normal to the two-dimensional periodic array, wherein each unit cell comprises a single aperture that is connected to an aperture in an adjacent unit cell in the first dimension but not in the second dimension, and wherein each aperture comprises a large sub-aperture that aids in coupling of the incident light and a small sub-aperture that funnels a significant fraction of the incident light power, and wherein the wavelength of the incident light is between 0.3 pm and 1000 pm, and wherein the thin conducting film has a thickness in a third dimension orthogonal to the first and second dimensions and wherein the thickness of the thin conducting film is subwavelength to the incident light, and wherein the apertures are unfilled.
2. The structure of claim 1 , wherein the large sub-aperture comprises a large rectangular slit and the small sub-aperture comprises a small rectangular slit, thereby providing a double-groove structure.
3. The structure of claim 2 , wherein the small rectangular slit has a width w x1 and the large rectangular slit has a larger width w x2 , and wherein neither w x1 =w x2 nor w x1 =0.
4. The structure of claim 1 , wherein at least one of the sub-apertures comprises a circular, elliptical, or diamond-shaped sub-aperture.
5. The structure of claim 1 , wherein the thin conducting film comprises a metal or a highly doped semiconductor.
6. The structure of claim 5 , wherein the metal comprises a noble metal.
7. The structure of claim 5 , wherein the metal comprises Au, Al, Ag, Ni, Cu, or W.
8. The structure of claim 5 , wherein the highly doped semiconductor comprises Si, GaAs, InGaAs, or InP.
9. The structure of claim 1 , wherein the thin conducting film is disposed on a dielectric substrate that is transparent to the incident light.
10. The structure of claim 9 , wherein the substrate comprises glass, quartz, calcium fluoride, barium fluoride, silicon, GaAs, or ZnSe.
11. The structure of claim 1 , wherein the wavelength of the incident light is between 3 μm and 20 μm.
12. The structure of claim 1 , wherein the unit cell comprises a square lattice with first and second periodicities equal to a and the incident light has a wavelength of λ, and wherein λ/a is greater than approximately 10.
13. The structure of claim 12 , wherein λla is greater than approximately 100.
14. The structure of claim 1 , wherein the periodic array comprises a square, rectangular, or rhomboidal lattice geometry.
15. The structure of claim 1 , wherein the thickness of the thin conducting film is less than a few hundred nanometers.